Description: Doxycycline is a broad-spectrum antibiotic. It is in the tetracycline family.

Dental uses: Doxycycline is prescribed for up to two weeks for different types of periodontal (gum) diseases. It is sometimes given to teens as well as adults.

Dosages for dental purposes: The typical adult dose is 100 milligrams to 200 milligrams once daily for up to two weeks.

Do not take doxycycline (or any tetracycline) with:

Dairy products (milk, yogurt)

Antacids (Tums, Rolaids, Maalox, Mylanta, Pepto-Bismol)

Iron supplements

Zinc supplements

These products reduce the amount of doxycycline that gets into the bloodstream.

As with all medicines, be sure to follow your doctor's prescription. Take regular-dose doxycycline for the prescribed length of time, even if you start to feel better. Do not stop taking it without talking to your doctor. Stopping an antibiotic too soon may cause bacteria to become resistant to antibiotics. This means the antibiotics won't work the next time.

Concerns and possible side effects: Tell your dentist and physician about all the medicines you take. This should include over-the-counter vitamins and herbal supplements. Also, let your dentist know if you have had a sensitive or allergic reaction to any medicine. If you are pregnant or nursing, or might be pregnant, talk to your primary care doctor before starting any new medicine. This also includes vitamins and supplements.

Penicillin VK often is the first drug prescribed for a gum infection. If it does not go away, the dentist may prescribe doxycycline, which has more side effects. Doxycycline's side effects include:

Making birth control pills less effective

Headache

Common cold

Flu-like symptoms

Nausea

Vomiting

Stomach pain

Diarrhea — This may be severe and may occur several months after you stop taking doxycycline. Check with your prescribing doctor before taking any medicine to treat diarrhea.

Vaginal yeast infections

Severe sunburn, if you do not protect yourself — Use sunscreen and avoid spending a lot of time in the sun.

Doxycycline (and all tetracyclines) should not be given to children under 8 years old or to pregnant women. These drugs can permanently stain teeth. They also can affect the structure of developing teeth.

Doxycycline can cause false results in some tests for sugar in the urine. Do not change your diet or dosage of your diabetes medicine before speaking to your physician.

Tell your doctor about any reaction to a prescribed medicine, no matter how minor it might be.